| On a list, in olden times | 25 |
| On a long project, perhaps | 26 |
| On a lounge chair, maybe | 24 |
| On a menu, for instance | 23 |
| On a moment's notice | 24 |
| On a par with, in France | 24 |
| On a par, in Orléans | 23 |
| On a plane, train or bus | 24 |
| On a plane, train, or bus | 25 |
| On a proportional basis | 23 |
| On a scale from one -- | 22 |
| On a shortage of know-how? | 26 |
| On a slow boat to China | 23 |
| On a slow boat to China, e.g. | 29 |
| On a vessel's left | 22 |
| On a voyage on the ocean | 24 |
| On a ___-to-know basis | 22 |
| ON address, or actress Lohan | 28 |
| ON address, or Disney duck | 26 |
| On again, as a lantern | 22 |
| On all ___ (crawling, say) | 26 |
| On an America's Cup yacht | 29 |
| On an enforced diet of sorts | 28 |
| On an even __ (steady) | 22 |
| On an even ___ (stable) | 23 |
| On an ocean liner, e.g. | 23 |
| On an ocean liner, maybe | 24 |
| On an ocean liner, perhaps | 26 |
| On an ocean liner, say | 22 |
| On an opponent's field | 26 |
| On and on and on and ... | 24 |
| On Cato's calendar | 22 |
| On display only: Abbr. | 22 |
| On edge with excitement | 23 |
| On edge, with 'up' | 26 |
| On either side of the center | 28 |
| On even terms, old-style | 24 |
| On every single occasion | 24 |
| On everyone's A-list | 24 |
| On everyone's mind | 22 |
| On fire in the kitchen | 22 |
| On fire, as a building | 22 |
| On fire, as some desserts | 25 |
| On fire, in restaurant lingo | 28 |
| On Golden Pond actor | 23 |
| On hand, as a touring troupe | 28 |
| On Hobbits, they make a point | 29 |
| On Hollywood Blvd., say | 23 |
| On intimate social terms with | 29 |
| On its way (or so they say) | 27 |
| On its way, as a letter | 23 |
| On its way, as a message | 24 |
| On its way, to oilmen? | 22 |
| On leave, for a swabbie | 23 |
| On life support, probably | 25 |
| On Mars, this is 687 days | 25 |
| On naval maneuvers, in a way | 28 |
| On one's last legs | 22 |
| On one's rocker, perhaps | 28 |
| On one's tax return | 23 |
| On one's __ (alert) | 23 |
| On one's ___ (alert) | 24 |
| On one's ___ (broke) | 24 |
| On one's ___ (destitute) | 28 |
| On one's ___ (indigent) | 27 |
| On one's ___ (submissive) | 29 |
| On Poseidon's territory | 27 |
| On Quint's Orca, perhaps | 28 |
| On sale, or taken off sale | 26 |
| On Soc. Sec., typically | 23 |
| On Social Security: Abbr. | 25 |
| On some naval maneuvers, e.g. | 29 |
| On spring's fringe? | 23 |
| On the -- (at variance) | 23 |
| On the -- (discreetly) | 22 |
| On the -- (hiding out) | 22 |
| On the -- (unfriend-ly) | 23 |
| On the -- of (close to) | 23 |
| On the --- (precisely) | 22 |
| On the 31st of February | 23 |
| On the affirmative side | 23 |
| On the Atlantic or Pacific | 26 |
| On the back burner, perhaps | 27 |
| On the ball or on the dot | 25 |
| On the best-dressed list | 24 |
| On the bride's mind | 23 |
| On the calm side, at sea | 24 |
| On the calmer side, at sea | 26 |
| On the canvas for good | 22 |
| On the canvas, informally | 25 |
| On the Caribbean, e.g. | 22 |
| On the Caribbean, poetically | 28 |
| On the clergyman's mind | 27 |
| On the court's roster | 25 |
| On the Dead or the Red | 22 |
| On the double, briefly | 22 |
| On the double, in memos | 23 |
| On the double, in the O.R. | 26 |
| On the double, in the OR | 24 |
| On the double, initially | 24 |